Neurofeedback is a form of biofeedback that uses electrical potentials in the brain to reinforce desired brain states through operant conditioning. This process is non-invasive neurotherapy and typically collects brain activity data using electroencephalography (EEG). Several neurofeedback protocols exist, with potential additional benefit from use of quantitative electroencephalography (QEEG) or functional magnetic resonance imaging (fMRI) to localize and personalize treatment. Related technologies include functional near-infrared spectroscopy-mediated (fNIRS) neurofeedback, hemoencephalography biofeedback (HEG), and fMRI biofeedback. Neurofeedback's benefits are unproven; improvements may stem more from placebo effects than direct brain regulation.
History In 1898, Edward Thorndike formulated the law of effect. In his work, he theorized that behavior is shaped by satisfying or discomforting consequences. This set the foundation for operant conditioning. In 1924, the German psychiatrist Hans Berger connected several electrodes to a patient's scalp and detected a small current by using a ballistic galvanometer. In his subsequent studies, Berger analyzed EEGs qualitatively, but in 1932, G. Dietsch applied Fourier analysis to seven EEG records and later became the first researcher to apply quantitative EEG (QEEG). In 1950, Neal E. Miller of Yale University was able to train mice to regulate their heartbeat frequency. Later on, he continued his work with humans, training them through auditory feedback. The first study to demonstrate neurofeedback was reported by Joe Kamiya in 1962. Kamiya's experiment had two parts: In the first part, a subject was asked to keep their eyes closed, and when a tone sounded, to say whether they were experiencing alpha waves. Initially, the subject would guess correctly about fifty percent of the time, but some subjects would eventually develop the ability to better distinguish between states. M. Barry Sterman trained cats to modify their EEG patterns to exhibit more of the so-called sensorimotor rhythm (SMR). He published this research in 1967. Sterman subsequently discovered that the SMR-trained cats were much more resistant to epileptic seizures after exposure to the convulsant chemical monomethylhydrazine than non-trained cats. In 1971, he reported similar improvements with an epileptic patient whose seizures could be controlled through SMR training. Joel Lubar contributed to the research of EEG biofeedback, starting with epilepsy and later with hyperactivity and ADHD.
Neuroplasticity In 2010, a study provided some evidence of neuroplastic changes occurring after brainwave training. In this study, half an hour of voluntary control of brain rhythms led to a lasting shift in cortical excitability and intracortical function. The authors observed that the cortical response to transcranial magnetic stimulation (TMS) was significantly enhanced after neurofeedback, persisted for at least twenty minutes, and was correlated with an EEG time-course indicative of activity-dependent plasticity A review of the relevant scientific literature has shown that systematic cognitive load from working on a computer (specifically, training subjects to monitor their brain functions by measuring brain waves and providing feedback), with a total training duration of 16 hours (a few hours of weekly performance), can affect brain structure and function depending on how the impact is performed.
Types of neurofeedback The term neurofeedback is not legally protected. There are various approaches that give feedback about neuronal activity, and as such are referred to as "neurofeedback" by their respective operators. Distinctions can be made on several levels. The first takes into account which technology is being used (EEG, fMRI, fNIRS, HEG). Nonetheless, further distinctions are crucial even within the realm of EEG neurofeedback, as different methodologies of analysis can be chosen, some of which are backed up by a higher number of peer-reviewed studies, whereas for others, scientific literature is scarce, and explanatory models are entirely missing. Despite these differences, a common denominator can be found in the requirement of providing feedback. Usually, feedback is provided by auditory or visual input. While original feedback was provided by sounding tones according to neurological activity, many new ways have been found. It is possible to listen to music or podcasts where the volume is controlled as feedback, for example. Often, visual feedback is used in the form of animations on a TV screen. Visual feedback can also be provided in combination with videos and films, or even during reading tasks where the brightness of the screen represents the direct feedback. Simple games can also be used, where the game itself is controlled by the brain activity. Recent developments have tried to incorporate virtual reality (VR), and controllers can already be used for more involved engagement with the feedback.
EEG neurofeedback
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